Apparatus for controlling turbine blade tip clearance and gas turbine including the same

ABSTRACT

An apparatus for controlling tip clearance between a turbine casing and a turbine blade is provided. The apparatus for controlling tip clearance includes a casing surrounding the turbine blade, a cooling plate installed in a groove and formed in a circumferential direction in the casing, the cooling plate being contracted by cold air supplied thereto, an upper plate mounted radially outside the cooling plate in the groove and having a plurality of cold air holes formed therein, a cylinder extending radially from an inner peripheral surface of the upper plate and having a plurality of cooling holes formed on a side thereof, and a ring segment mounted radially inside the cooling plate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No.10-2020-0038944, filed on Mar. 31, 2020, the disclosure of which isincorporated herein by reference in its entirety.

BACKGROUND Technical Field

Apparatuses and methods consistent with exemplary embodiments relate toan apparatus for controlling turbine blade tip clearance and a gasturbine including the same.

Description of the Related Art

Turbines are machines that obtain a rotational force by impingement orreaction force using a flow of a compressible fluid such as steam orgas, and include a steam turbine using steam, a gas turbine using hotcombustion gas, and so on.

The gas turbine includes a compressor, a combustor, and turbine. Thecompressor has an air inlet for introduction of air thereinto, andincludes a plurality of compressor vanes and a plurality of compressorblades alternately arranged in a compressor casing.

The combustor supplies fuel to air compressed by the compressor andignites a mixture thereof with a burner to produce high-temperature andhigh-pressure combustion gas.

The turbine includes a plurality of turbine vanes and a plurality ofturbine blades alternately arranged in a turbine casing. In addition, arotor is disposed to pass through centers of the compressor, thecombustor, the turbine, and an exhaust chamber.

The rotor is rotatably supported at both ends thereof by bearings. Therotor has a plurality of disks fixed thereto, and a plurality of bladesare connected to each of the disks while a drive shaft of a generator isconnected to an end of the exhaust chamber.

The gas turbine is advantageous in that consumption of lubricant isextremely low due to an absence of mutual friction parts such as apiston-cylinder because the gas turbine does not have a reciprocatingmechanism such as a piston in a four-stroke engine. Therefore, anamplitude, which is a characteristic of reciprocating machines, isgreatly reduced, and the gas turbine has an advantage of high-speedmotion.

The operation of the gas turbine is briefly described. That is, the aircompressed by the compressor is mixed with fuel for combustion toproduce high-temperature and high-pressure combustion gas which isinjected into the turbine, and the injected combustion gas generates arotational force while passing through the turbine vanes and turbineblades, thereby rotating the rotor.

In this case, a gap defined as a tip clearance is formed between theturbine casing and each of the plurality of blades. If the tip clearanceis increased above an acceptable level, an amount of combustion gas thatis not activated and is discharged between the turbine casing and theblade, reducing an overall efficiency of the gas turbine. In contrast,if the tip clearance decreases below an appropriate level, the blade mayscratch the inner wall of the turbine casing. Therefore, adjusting thetip clearance of the turbine to an appropriate level is closely relatedto improving the performance of the gas turbine.

SUMMARY

Aspects of one or more exemplary embodiments provide an apparatus forcontrolling turbine blade tip clearance which allows a cooling plate tohave an improved shape to supply cold air more efficiently, therebyenabling the cooling plate to contract further in a radial direction,and a gas turbine including the same.

Additional aspects will be set forth in part in the description whichfollows and, in part, will become apparent from the description, or maybe learned by practice of the exemplary embodiments.

According to an aspect of an exemplary embodiment, there is provided anapparatus for controlling tip clearance between a turbine casing and aturbine blade, the apparatus including: a casing surrounding the turbineblade, a cooling plate installed in a groove and formed in acircumferential direction in the casing, the cooling plate beingcontracted by cold air supplied thereto, an upper plate mounted radiallyoutside the cooling plate in the groove and having a plurality of coldair holes formed therein, a cylinder extending radially from an innerperipheral surface of the upper plate and having a plurality of coolingholes formed on a side thereof, and a ring segment mounted radiallyinside the cooling plate.

The plurality of cold air holes may include a first cold air hole forsupplying cold air into the cylinder, and a plurality of second cold airholes arranged around the first cold air hole to supply cold air to aspace between an outside of the cylinder and the inside of the coolingplate.

The plurality of second cold air holes may be obliquely formed to supplycold air toward an outer peripheral surface of the cylinder.

The cylinder may have a lower end integrally connected to an uppersurface of the cooling plate.

The cooling plate may include a body disposed in the groove of thecasing, a mounting groove formed radially inside the body, and a pair ofside walls extending outward from both sides on a radially outerperipheral surface of the body.

The cylinder may include a plurality of cylinders arranged on the upperplate corresponding to one ring segment.

The plurality of second cooling holes may include four second coolingholes arranged at equal intervals around the first cooling hole.

The plurality of second cooling holes may include eight second coolingholes arranged around the first cooling hole.

Four of the plurality of second cooling holes may be arranged ondifferent concentric circles around the first cooling hole, compared tothe other four second cooling holes.

The plurality of cooling holes may be obliquely formed on a side wall ofthe cylinder.

According to an aspect of another exemplary embodiment, there isprovided a gas turbine including: a compressor configured to compressoutside air, a combustor configured to mix fuel with the air compressedby the compressor to burn a mixture thereof, a turbine including aplurality of turbine blades in a turbine casing rotated by combustiongas discharged from the combustor, and an apparatus for controlling tipclearance between the turbine casing and the turbine blade. Theapparatus for controlling tip clearance may include a casing surroundingthe turbine blade, a cooling plate installed in a groove and formed in acircumferential direction in the casing, the cooling plate beingcontracted by cold air supplied thereto, an upper plate mounted radiallyoutside the cooling plate in the groove and having a plurality of coldair holes formed therein, a cylinder extending radially from an innerperipheral surface of the upper plate and having a plurality of coolingholes formed on a side thereof, and a ring segment mounted radiallyinside the cooling plate.

The plurality of cold air holes may include a first cold air hole forsupplying cold air into the cylinder, and a plurality of second cold airholes arranged around the first cold air hole to supply cold air to aspace between an outside of the cylinder and the inside of the coolingplate.

The plurality of second cold air holes may be obliquely formed to supplycold air toward an outer peripheral surface of the cylinder.

The cylinder may have a lower end integrally connected to an uppersurface of the cooling plate.

The cooling plate may include a body disposed in the groove of thecasing, a mounting groove formed radially inside the body, and a pair ofside walls extending outward from both sides on a radially outerperipheral surface of the body.

The cylinder may include a plurality of cylinders arranged on the upperplate corresponding to one ring segment.

The plurality of second cooling holes may include four second coolingholes arranged at equal intervals around the first cooling hole.

The plurality of second cooling holes may include eight second coolingholes arranged around the first cooling hole.

Four of the plurality of second cooling holes may be arranged ondifferent concentric circles around the first cooling hole, compared tothe other four second cooling holes.

The plurality of cooling holes may be obliquely formed on a side wall ofthe cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects will become more apparent from the followingdescription of the exemplary embodiments with reference to theaccompanying drawings, in which:

FIG. 1 is a partial cutaway perspective view illustrating a gas turbineaccording to an exemplary embodiment;

FIG. 2 is a cross-sectional view illustrating a schematic structure ofthe gas turbine according to the exemplary embodiment;

FIG. 3 is a partial cross-sectional view illustrating an internalstructure of the gas turbine according to the exemplary embodiment;

FIG. 4 is a perspective view illustrating a tip clearance controlapparatus according to an exemplary embodiment;

FIG. 5 is a cross-sectional view illustrating the tip clearance controlapparatus according to the exemplary embodiment;

FIG. 6 is a schematic view illustrating a flow of cold air supplied to acooling plate through an upper plate according to an exemplaryembodiment;

FIG. 7A is a perspective view illustrating a state in which a ringsegment is coupled to the cooling plate according to an exemplaryembodiment;

FIG. 7B is a side view illustrating a state in which the ring segment iscoupled to the cooling plate according to the exemplary embodiment;

FIG. 8A is a view illustrating an amount of radial deformation of thecooling plate before supplying cold air to the tip clearance controlapparatus according to an exemplary embodiment;

FIG. 8B is a view illustrating an amount of radial deformation of thecooling plate after supplying cold air to the tip clearance controlapparatus according to an exemplary embodiment;

FIG. 9A is a perspective view illustrating a temperature distributionwhen three cylinders are disposed in one cooling plate segment;

FIG. 9B is a view illustrating an amount of radial deformation of thecooling plate when three cylinders are disposed in one cooling platesegment;

FIGS. 10A to 10E are schematic views illustrating other examples ofsecond cold air holes formed in the upper plate; and

FIGS. 11A to 11D are schematic views illustrating other examples ofcooling holes formed in each cylinder.

DETAILED DESCRIPTION

Various modifications and various embodiments will be described below indetail with reference to the accompanying drawings so that those skilledin the art can easily carry out the disclosure. It should be understood,however, that the various embodiments are not for limiting the scope ofthe disclosure to the specific embodiment, but they should beinterpreted to include all modifications, equivalents, and alternativesof the embodiments included within the spirit and scope disclosedherein.

The terminology used herein is for the purpose of describing specificembodiments only and is not intended to limit the scope of thedisclosure. The singular expressions “a”, “an”, and “the” are intendedto include the plural expressions as well unless the context clearlyindicates otherwise. In the disclosure, terms such as “comprises”,“includes”, or “have/has” should be construed as designating that thereare such features, integers, steps, operations, components, parts,and/or combinations thereof, not to exclude the presence or possibilityof adding of one or more of other features, integers, steps, operations,components, parts, and/or combinations thereof.

Further, terms such as “first,” “second,” and so on may be used todescribe a variety of elements, but the elements should not be limitedby these terms. The terms are used simply to distinguish one elementfrom other elements. The use of such ordinal numbers should not beconstrued as limiting the meaning of the term. For example, thecomponents associated with such an ordinal number should not be limitedin the order of use, placement order, or the like. If necessary, eachordinal number may be used interchangeably.

Hereinafter, a tip clearance control apparatus and a gas turbineincluding the same according to exemplary embodiments will be describedwith reference to the accompanying drawings. It should be noted thatlike reference numerals refer to like parts throughout thespecification. In certain embodiments, a detailed description offunctions and configurations well known in the art may be omitted toavoid obscuring appreciation of the disclosure by a person of ordinaryskill in the art. For the same reason, some components may beexaggerated, omitted, or schematically illustrated in the accompanyingdrawings.

FIG. 1 is a partial cutaway perspective view illustrating a gas turbineaccording to an exemplary embodiment. FIG. 2 is a cross-sectional viewillustrating a schematic structure of the gas turbine according to theexemplary embodiment. FIG. 3 is a partial cross-sectional viewillustrating an internal structure of the gas turbine according to theexemplary embodiment.

Referring to FIG. 1 , the gas turbine 1000 according to the exemplaryembodiment includes a compressor 1100, a combustor 1200, and a turbine1300. The compressor 1100 including a plurality of blades 1110 arrangedradially rotates the blades 1110, and air is compressed by rotation ofthe blades 1110 and flows. A size and installation angle of each of theblades 1110 may vary depending on an installation position thereof. Thecompressor 1100 may be directly or indirectly connected to the turbine1300, to receive some of the power generated by the turbine 1300 and usethe received power to rotate the blades 1110.

The air compressed by the compressor 1100 flows to the combustor 1200.The combustor 1200 includes a plurality of combustion chambers 1210 andfuel nozzle modules 1220 arranged annularly.

Referring to FIG. 2 , the gas turbine 1000 according to the exemplaryembodiment includes a housing 1010 and a diffuser 1400 disposed behindthe housing 1010 to discharge the combustion gas passing through theturbine 1300. The combustor 1200 is disposed in front of the diffuser1400 to combust the compressed air supplied thereto.

Based on the direction of an air flow, the compressor 1100 is disposedat an upstream side, and the turbine 1300 is disposed at a downstreamside. A torque tube 1500 serving as a torque transmission member fortransmitting the rotational torque generated in the turbine 1300 to thecompressor 1100 is disposed between the compressor 1100 and the turbine1300.

The compressor 1100 includes a plurality of compressor rotor disks 1120,each of which is fastened by a tie rod 1600 to prevent axial separationin an axial direction of the tie rod 1600.

For example, the compressor rotor disks 1120 are axially aligned in astate in which the tie rod 1600 forming a rotary shaft passes throughthe centers of the compressor rotor disks 1120. Here, adjacentcompressor rotor disks 1120 are arranged so that facing surfaces thereofare in tight contact with each other by being pressed by the tie rod1600. The adjacent compressor rotor disks 1120 cannot rotate because ofthis arrangement.

Each of the compressor rotor disks 1120 has a plurality of blades 1110radially coupled to an outer peripheral surface thereof. Each of theblades 1110 has a dovetail 1112 fastened to the compressor rotor disk1120.

A plurality of vanes are fixedly arranged between each of the compressorrotor disks 1120 in the housing 1010. While the compressor rotor disks1120 rotate along with a rotation of the tie rod 1600, the vanes fixedto the housing 1010 do not rotate. The vanes guide the flow of thecompressed air moved from front-stage blades 1110 to rear-stage blades1100.

The dovetail 1112 may be fastened by a tangential type or an axial type,which may be selected according to a structure of a gas turbine. Thedovetail 1112 may have a dovetail shape or a fir-tree shape. In somecases, the blades 1110 may be fastened to the compressor rotor disks1120 by using other types of fastening members such as a key or a bolt.

The tie rod 1600 is disposed to pass through centers of the plurality ofcompressor rotor disks 1120 and turbine rotor disks 1322. The tie rod1600 may be a single tie rod or a plurality of tie rods. One end of thetie rod 1600 is fastened to a most upstream compressor rotor disk, andthe other end thereof is fastened by a fixing nut 1450.

It is understood that the type of the tie rod 1600 may not be limited tothe example illustrated in FIG. 2 , and may be changed or vary accordingto one or more other exemplary embodiments. For example, a single tierod may be disposed to pass through the centers of the rotor disks, aplurality of tie rods may be arranged circumferentially, or acombination thereof may be used.

Also, in order to increase the pressure of fluid and adjust an actualinflow angle of the fluid entering into an inlet of the combustor, adeswirler serving as a guide vane may be installed at the rear stage ofthe diffuser of the compressor 1100 so that the actual inflow anglematches a designed inflow angle.

The combustor 1200 mixes fuel with the introduced compressed air, burnsa fuel-air mixture to produce high-temperature and high-pressurecombustion gas with high energy, and increases the temperature of thecombustion gas to a temperature at which the combustor and the turbinecomponents are able to be resistant to heat through an isobariccombustion process.

A plurality of combustors constituting the combustor 1200 may bearranged in the housing in a form of a cell. Each of the combustors mayinclude a burner having a fuel injection nozzle and the like, acombustor liner defining a combustion chamber, and a transition pieceserving as a connection between the combustor and the turbine.

The combustor liner provides a combustion space in which the fuelinjected by the fuel injection nozzle is mixed with the compressed airsupplied from the compressor. The combustor liner may include a flamecontainer providing the combustion space in which the mixture of air andfuel is burned, and a flow sleeve defining an annular space whilesurrounding the flame container. The fuel injection nozzle is coupled toa front end of the combustor liner, and an ignition plug is coupled to aside wall of the combustor liner.

The transition piece is connected to a rear end of the combustor linerto transfer the combustion gas toward the turbine. An outer wall of thetransition piece is cooled by the compressed air supplied from thecompressor to prevent the transition piece from being damaged due to thehigh temperature of the combustion gas.

To this end, the transition piece has cooling holes through which thecompressed air is injected, and the compressed air cools the inside ofthe transition piece and then flows toward the combustor liner.

The compressed air that has cooled the transition piece may flow into anannular space of the combustor liner, and may be supplied as a coolingair through the cooling holes formed in the flow sleeve from the outsideof the flow sleeve to an outer wall of the combustor liner.

The high-temperature and high-pressure combustion gas ejected from thecombustor 1200 is supplied to the turbine 1300. The suppliedhigh-temperature and high-pressure combustion gas expands and appliesimpingement or reaction force to the turbine blades to generaterotational torque. A portion of the obtained rotational torque istransmitted via the torque tube to the compressor, and the remainingportion which is the excessive torque is used to drive a generator orthe like.

The turbine 1300 basically has a structure similar to the compressor1100. That is, the turbine 1300 includes a turbine rotor 1320 similar tothe rotor of the compressor 1100. The turbine rotor 1320 includes aplurality of turbine rotor disks 1322 and a plurality of turbine blades1324 arranged radially. The turbine blades 1324 may be coupled to theturbine rotor disk 1322 in a dovetail coupling manner or the like.

In addition, a plurality of turbine vanes 1314 fixed to a turbine casing1312 are provided between the turbine blades 1324 of the turbine rotordisk 1322 to guide a flow direction of the combustion gas passingthrough the turbine blades 1324. In this case, the turbine casing 1312and the turbine vanes 1314 corresponding to a fixing body may becollectively referred to as a turbine stator 1310 in order todistinguish them from the turbine rotor 1320 corresponding to a rotatingbody.

Referring to FIG. 3 , the turbine vanes 1314 are fixedly mounted in theturbine casing 1312 by a vane carrier 200, which is an endwall coupledto inner and outer ends of each of the turbine vanes 1314. On the otherhand, a ring segment 150 is mounted to the inner surface of the turbinecasing at a position facing the outer end of each of the turbine blades1324, with a predetermined gap. That is, the gap formed between the ringsegment 150 and the outer end of the turbine blade 1324 is defined as atip clearance.

Referring back to FIG. 2 , the turbine blade 1324 comes into directcontact with high-temperature and high-pressure combustion gas. Theturbine blade 1324 may be deformed by the combustion gas, and theturbine 1300 may be damaged by the deformation of the turbine blade1324. In order to prevent deformation due to such high temperature, abranch passage 1800 may be formed between the compressor 1100 and theturbine 1300 so that a part of the air having a temperature relativelylower than that of the combustion gas may be branched into thecompressor 1100 and supplied to the turbine blade 1324.

The branch passage 1800 may be formed outside the compressor casing ormay be formed inside the compressor casing by passing through thecompressor rotor disk 1120. The branch passage 1800 may supply thecompressed air branched from the compressor 1100 to the turbine rotordisk 1322. The compressed air supplied to the turbine rotor disk 1322flows radially outward, and may be supplied to the turbine blade 1324 tocool the turbine blade 1324. In addition, the branch passage 1800connected to the outside of the housing 1010 may supply the compressedair branched from the compressor 1100 to the turbine casing 1312 to coolthe inside of the turbine casing 1312. The branch passage 1800 may beprovided with a valve 1820 in a middle thereof to selectively supplycompressed air. The branch passage 1800 may be connected to a heatexchanger to selectively further cool the compressed air prior tosupply.

FIG. 4 is a perspective view illustrating a tip clearance controlapparatus according to an exemplary embodiment. FIG. 5 is across-sectional view illustrating the tip clearance control apparatusaccording to the exemplary embodiment. FIG. 6 is a schematic viewillustrating a flow of cold air supplied to a cooling plate through anupper plate according to an exemplary embodiment.

Referring to FIGS. 4 to 6 , the tip clearance control apparatus mayinclude a casing 110 surrounding a turbine blade 1324, a cooling plate120 installed in a groove and formed in the circumferential direction inthe casing and contracted by the supplied cold air, an upper plate 130mounted radially outside the cooling plate 120 in the groove and havinga plurality of cold air holes 132 and 134 formed therein, a cylinder 140extending radially from the inner peripheral surface of the upper plate130 and having a plurality of cooling holes 142 formed on the sidethereof, and a ring segment 150 mounted radially inside the coolingplate 120.

The casing 110 is a turbine casing disposed to be spaced apart from theends of a plurality of turbine blades 1324 by a predetermined distance.The groove may be formed in a circumferential direction at a position inwhich each ring segment 150 is mounted in the casing 110.

The cooling plate 120 may be installed in the groove of the casing 110,and may be formed of a plurality of segments arranged in thecircumferential direction. FIGS. 4 and 5 illustrate that mounting ribs126 are formed at both upper ends of side walls 125 of the cooling plate120. However, it is understood that the mounting ribs 126 may not belimited to the example illustrated in FIGS. 4 and 5 , and may be changedor vary according to one or more other exemplary embodiments. Forexample, the cooling plate 120 includes a plurality of segments whichmay each be radially supported on the circumferential side, and even ifthere is no mounting rib, the segments of the cooling plate 120 may befixedly mounted in the groove of the casing 110.

The ring segment 150 may be mounted in a mounting structure providedradially inside the cooling plate 120. The ring segment 150 may includea body 152 in a form of a plate bent in a circumferential direction, anda mounting rib portion 154 extending outward from the radially outersurface of the body 152 and then extending axially outward.

The cooling plate 120 may include a body 122 disposed in the groove ofthe casing 110, a mounting groove 124 formed radially inside the body122, and a pair of side walls 125 extending outwardly from both sides onthe radially outer peripheral surface of the body 122.

The body 122 may be in a form of an arc-shaped plate segment bent in thecircumferential direction.

The mounting groove 124 is formed radially inside the body 122. Themounting groove 124 may form a groove for inserting the mounting ribportion 154 of the ring segment 150, in a manner that extends radiallyinward from both axial edges of the inner peripheral surface and bendsso that inner ends thereof face each other.

The pair of side walls 125 may be in a form of a rib extending outwardlyfrom both edges on the radially outer peripheral surface of the body122. As described above, the mounting rib 126 may or may not be formedon the axially outside the upper end of each side wall 125.

Here, the pair of side walls 125 are referred to as side walls becausethey extend from the edge of the body 122 and are in contact with theinner surface of the groove of the casing 110. However, the side walls125 may be in the form of a rib such as a fin to serve as a cooling finto which cold air is supplied.

The upper plate 130 is mounted radially outside the cooling plate 120 inthe groove of the casing 110. The cooling plate 120 may be in a form ofan arc-shaped plate segment bent in the circumferential direction. Theplurality of cold air holes 132 and 134 may be formed radially throughthe cooling plate 120 at a portion to which the cylinder 140 isconnected and a portion around the cylinder 140.

The cylinder 140 may be formed integrally by extending radially to theinner peripheral surface of the upper plate 130. The cylinder 140 may bein a form of a circular pipe with a closed lower end. The plurality ofcooling holes 142 may be formed on a lower side of the cylinder 140. Thelower end of the cylinder 140 comes into contact with the body 122 ofthe cooling plate 120.

The plurality of cold air holes formed in the upper plate 130 mayinclude a first cold air hole 132 for supplying cold air to the cylinder140, and a plurality of second cold air holes 134 arranged around thefirst cold air hole 132 to supply cold air to a space between theoutside of the cylinder 140 and the inside of the cooling plate 120.

As illustrated in FIGS. 4 to 6 , the first cold air hole 132 is formedthrough the upper plate 130 in the center to which the cylinder 140 isconnected to supply cold air into the cylinder 140. The cold airsupplied into the cylinder 140 may be supplied to the space between thecylinder 140 and the cooling plate 120 through the plurality of coolingholes 142.

The plurality of second cooling holes 134 may include four or moresecond cooling holes formed around the first cooling hole 132. Theplurality of second cooling holes 134 may be arranged such that animaginary concentric circle connecting centers of the second coolingholes 134 is larger than an outer diameter of the cylinder 140.

The plurality of second cooling holes 134 may be obliquely formed tosupply cool air toward the outer peripheral surface of the cylinder 140.The lower end of the cylinder 140 is in contact with the cooling plate120. Therefore, when the cylinder 140 is cooled, the cold air may bedelivered to the cooling plate 120 by conduction. To this end, the coldair supplied from the radially outer side of the upper plate 130 mayintensively cool the cylinder 140 through the plurality of secondcooling air holes 134.

It is preferable that the lower end of the cylinder 140 is integrallyconnected to an upper surface of the body 122 of the cooling plate 120.Here, the upper surface of the body 122 is based on FIG. 5 , and may bereferred to as a radially outer peripheral surface of the body 122. Inthis way, a 3D structure in which the upper plate 130, the cylinder 140,and the cooling plate 120 are formed integrally with each other may bemanufactured by 3D printing. As the cylinder 140 is integrally connectedwith the cooling plate 120, a large amount of cold air may be deliveredto the cooling plate 120 from the cylinder 140 which is intensivelycooled by cold air, thereby enabling the cooling plate 120 to contractfurther.

FIG. 7A is a perspective view illustrating a state in which the ringsegment is coupled to the cooling plate according to the exemplaryembodiment, and FIG. 7B is a side view illustrating a state in which thering segment is coupled to the cooling plate according to the exemplaryembodiment. FIG. 8A is a view illustrating an amount of radialdeformation of the cooling plate before supplying cold air to the tipclearance control apparatus according to an exemplary embodiment, andFIG. 8B is a view illustrating an amount of radial deformation of thecooling plate after supplying cold air to the tip clearance controlapparatus according to an exemplary embodiment. FIG. 9A is a perspectiveview illustrating a temperature distribution when three cylinders aredisposed in one cooling plate segment, and FIG. 9B is a viewillustrating an amount of radial deformation of the cooling plate whenthree cylinders are disposed in one cooling plate segment.

Referring to FIGS. 7A and 7B, when the gas turbine is operated whilesupplying cold air to the cooling plate 120, it can be seen that theminimum displacement of the inner end of the ring segment 150 is about4.58 mm and the maximum displacement of the outer end of the upper plate130 is about 5.42 mm in the distribution of the amount of deformation inthe radial direction of the upper plate 130, the cooling plate 120, andthe ring segment 150.

Referring to FIG. 8A, when the gas turbine is operated without supplyingcold air to the cooling plate 120, it can be seen that the minimumdisplacement of the inner end of the ring segment 150 is about 4.90 mmand the maximum displacement of the outer end of the upper plate 130 isabout 5.86 mm in the distribution of the amount of deformation in theradial direction of the upper plate 130, the cooling plate 120, and thering segment 150.

Referring to FIG. 8B, when the gas turbine is operated while supplyingcold air to the cooling plate 120, it can be seen that the minimumdisplacement of the inner end of the ring segment 150 is about 4.58 mmand the maximum displacement of the outer end of the cooling plate 120is about 4.98 mm in the distribution of the amount of deformation in theradial direction of the upper plate 130, the cooling plate 120, and thering segment 150.

Accordingly, the tip clearance control apparatus can control the amountof radial deformation of the cooling plate such that the cooling plateis displaced at a minimum of about 0.32 mm and a maximum of about 0.43mm depending on whether cold air is supplied.

Referring to FIG. 9A, the cylinder 140 may include a plurality ofcylinders (e.g., three) arranged on the upper plate 130 corresponding toone ring segment 150. In this case, when the gas turbine is operatedwhile supplying cold air to the tip clearance control apparatus, thetemperature distribution showed that the lowest temperature outside thecasing was about 338° C. and the highest temperature inside the ringsegment was about 884° C. As such, when the cooling plate is cooled, itcontracts radially inward. Therefore, it is possible to further reducethe tip clearance between the end of the turbine blade and the ringsegment mounted on the cooling plate.

Referring to FIG. 9B, when three cylinders 140 are disposed on the upperplate 130, when the gas turbine is operated while supplying cold air tothe cooling plate, it can be seen that the minimum displacement of theinner end of the ring segment is about 4.34 mm and the maximumdisplacement of the outer end of the upper plate is about 5.17 mm in thedistribution of the amount of deformation in the radial direction of theupper plate, the cooling plate, and the ring segment.

Accordingly, the tip clearance control apparatus can control the amountof radial deformation of the cooling plate such that the cooling plateis displaced at a minimum of about 0.56 mm and a maximum of about 0.69mm depending on whether cold air is supplied. It can be seen that whenmore cylinders are arranged in this way, the cooling plate movesradially over a wider range than when providing one cylinder.

FIGS. 10A to 10E are schematic views illustrating other examples ofsecond cold air holes formed in the upper plate. FIGS. 11A to 11D areschematic views illustrating other examples of cooling holes formed inthe cylinder.

Referring to FIG. 10A, the plurality of second cooling holes 134 mayinclude four second cooling holes 134 arranged at equal intervals aroundthe first cooling hole 132 in the upper plate 130. The first coolinghole 132 may have a diameter larger than or equal to each second coolinghole 134. Here, the outermost circle represents a portion in which thecold air holes 132 and 134 are formed in the upper plate 130. Afterseparately manufacturing a structure in which the cylinder 140 isintegrally formed with a circular disk, the circular disk may beinserted into a circular hole formed in the upper plate 130 andassembled by welding or the like.

Referring to FIG. 10B, the plurality of second cooling holes 134 mayinclude eight second cooling holes 134 arranged at equal intervalsaround the first cooling hole 132 in the upper plate 130. The more thesecond cold air hole 134 is formed, the more cold air can be suppliedtoward the outer peripheral surface of the cylinder 140 through thehole.

Referring to FIG. 10C, the plurality of second cooling holes 134 mayinclude eight second cooling holes 134 arranged around the first coolinghole 132 in the upper plate 130, in which case four second cooling holes134 having a relatively large diameter and four second cold air holes134 having a relatively small diameter may be alternately disposed.

Referring to FIG. 10D, four of the plurality of second cooling holes 134may be arranged on different concentric circles around the first coolinghole 132 compared to the other four second cooling holes 134. That is,the four second cooling holes 134 may be disposed on a virtualconcentric circle having a relatively small diameter based on the centerof the first cooling hole 132, and the other four second cooling holes134 may be disposed on a virtual concentric circle having a relativelylarge diameter based on the center of the first cooling hole 132.

Referring to FIG. 10E, the plurality of second cooling holes 134 may beformed to be inclined toward the center of the first cooling hole 132,and inclined in a virtual concentric circle passing through the secondcooling holes 134. In this case, the cold air passing through the secondcold air holes 134 is not only guided to be supplied toward the outerperipheral surface of the cylinder 140, but also guided to rotate andflow in the space between the outside of the cylinder 140 and the insideof the cooling plate 120.

Referring to FIG. 11A, the plurality of cooling holes 142 formed on theside wall of the cylinder 140 may be formed in the left-right direction,that is, in the axial direction of the turbine.

Referring to FIG. 11B, the plurality of cooling holes 142 may includetwo or more sets of cooling holes formed at different radial heights onthe side wall of the cylinder 140. The more the number of cooling holes142 is, the more cold air passes through the cooling holes 142.Therefore, cooling performance can be further improved.

Referring to FIG. 11C, the plurality of cooling holes 142 may beobliquely formed on the side wall of the cylinder 140. For example, theplurality of cooling holes 142 may be obliquely formed so as tocommunicate from the upper inner side to the lower outer side of thecylinder 140. When the cooling holes 142 are obliquely formed in thisway, the path in which the cool air flows through the holes becomeslonger. Therefore, cooling performance can be further improved.

Referring to FIG. 11D, the plurality of cooling holes 142 communicatewith the inside of the cylinder 140, and the left and right coolingholes 142 may be formed to have the same angle of inclination. Here,virtual lines passing through centers of the two cooling holes 142 onboth sides may meet at the inner center of the cylinder 140. Theplurality of cooling holes 142 may include three sets of cooling holesformed on the side wall of the cylinder 140.

When the gas turbine starts to operate, the turbine blade 1324 heats uprapidly. Accordingly, the tip clearance between the ring segment 150 andthe turbine blade 1324 becomes small. Therefore, at the time ofstarting, heated air is supplied to the cooling plate 120 to move thering segment 150 radially outward, thereby preventing the end of theturbine blade 1324 from contacting the ring segment 150.

Because the tip clearance increases under normal conditions when the gasturbine is operated at a constant rotational speed, cold air is suppliedto the cooling plate 120 to move the ring segment 150 radially inward,thereby keeping the tip clearance small at an appropriate interval.

As described above, according to the apparatus for controlling turbineblade tip clearance and the gas turbine including the same, because theshape of the cooling plate has been improved to supply cold air moreefficiently, the cooling plate can contract further in the radialdirection.

Accordingly, the ring segment mounted on the cooling plate can movefurther in the radial direction, and the turbine blade tip clearance canbe adjusted over a wider range.

While one or more exemplary embodiments have been described withreference to the accompanying drawings, it will be apparent to thoseskilled in the art that various variations and modifications in form anddetails may be made by adding, changing, or removing components withoutdeparting from the spirit and scope of the disclosure as defined in theappended claims, and these variations and modifications fall within thespirit and scope of the disclosure as defined in the appended claims.Accordingly, the description of the exemplary embodiments should beconstrued in a descriptive sense only and not to limit the scope of theclaims, and many alternatives, modifications, and variations will beapparent to those skilled in the art.

What is claimed is:
 1. An apparatus for controlling tip clearancebetween a turbine casing and a turbine blade, the apparatus comprising:a casing surrounding the turbine blade; a cooling plate installed in agroove of the turbine casing and formed in a circumferential directionin the casing, the cooling plate being contacted by cold air suppliedthereto; an upper plate mounted in the groove of the turbine casingradially outside the cooling plate and having a plurality of cold airholes formed therein; a cylinder integrally extending radially inwardlyfrom an inner peripheral surface of the upper plate and having aplurality of cooling holes formed on a side thereof; and a ring segmentmounted radially inside the cooling plate.
 2. The apparatus according toclaim 1, wherein the plurality of cold air holes comprises a first coldair hole for supplying cold air into the cylinder, and a plurality ofsecond cold air holes arranged around the first cold air hole to supplycold air to a space between an outside of the cylinder and the inside ofthe cooling plate.
 3. The apparatus according to claim 2, wherein theplurality of second cold air holes are obliquely formed to supply coldair toward an outer peripheral surface of the cylinder.
 4. The apparatusaccording to claim 2, wherein the plurality of second cooling holesinclude four second cooling holes arranged at equal intervals around thefirst cooling hole.
 5. The apparatus according to claim 2, wherein theplurality of second cooling holes include eight second cooling holesarranged around the first cooling hole.
 6. The apparatus according toclaim 5, wherein four of the plurality of second cooling holes arearranged on different concentric circles around the first cooling hole,compared to the other four second cooling holes.
 7. The apparatusaccording to claim 1, wherein the cylinder has a lower end integrallyconnected to an upper surface of the cooling plate.
 8. The apparatusaccording to claim 1, wherein the cooling plate comprises a bodydisposed in the groove of the casing, a mounting groove formed radiallyinside the body, and a pair of side walls extending outward from bothsides on a radially outer peripheral surface of the body.
 9. Theapparatus according to claim 1, wherein the cylinder includes aplurality of cylinders arranged on the upper plate corresponding to onering segment.
 10. The apparatus according to claim 1, wherein theplurality of cooling holes are obliquely formed on a side wall of thecylinder.
 11. A gas turbine comprising: a compressor configured tocompress outside air; a combustor configured to mix fuel with the aircompressed by the compressor to burn a mixture thereof; a turbinecomprising a plurality of turbine blades in a turbine casing rotated bycombustion gas discharged from the combustor to generate power; and anapparatus for controlling tip clearance between the turbine casing andthe turbine blade, wherein the apparatus for controlling tip clearancecomprises: a casing surrounding the turbine blade; a cooling plateinstalled in a groove of the turbine casing and formed in acircumferential direction in the casing, the cooling plate beingcontacted by cold air supplied thereto; an upper plate mounted in thegroove of the turbine casing radially outside the cooling plate andhaving a plurality of cold air holes formed therein; a cylinderintegrally extending radially inwardly from an inner peripheral surfaceof the upper plate and having a plurality of cooling holes formed on aside thereof; and a ring segment mounted radially inside the coolingplate.
 12. The gas turbine according to claim 11, wherein the pluralityof cold air holes comprises a first cold air hole for supplying cold airinto the cylinder, and a plurality of second cold air holes arrangedaround the first cold air hole to supply cold air to a space between anoutside of the cylinder and the inside of the cooling plate.
 13. The gasturbine according to claim 12, wherein the plurality of second cold airholes are obliquely formed to supply cold air toward an outer peripheralsurface of the cylinder.
 14. The gas turbine according to claim 12,wherein the plurality of second cooling holes include four secondcooling holes arranged at equal intervals around the first cooling hole.15. The gas turbine according to claim 12, wherein the plurality ofsecond cooling holes include eight second cooling holes arranged aroundthe first cooling hole.
 16. The gas turbine according to claim 15,wherein four of the plurality of second cooling holes are arranged ondifferent concentric circles around the first cooling hole, compared tothe other four second cooling holes.
 17. The gas turbine according toclaim 11, wherein the cylinder has a lower end integrally connected toan upper surface of the cooling plate.
 18. The gas turbine according toclaim 11, wherein the cooling plate comprises a body disposed in thegroove of the casing, a mounting groove formed radially inside the body,and a pair of side walls extending outward from both sides on a radiallyouter peripheral surface of the body.
 19. The gas turbine according toclaim 11, wherein the cylinder includes a plurality of cylindersarranged on the upper plate corresponding to one ring segment.
 20. Thegas turbine according to claim 11, wherein the plurality of coolingholes are obliquely formed on a side wall of the cylinder.